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11/6/2012 8:35:38 PM EDT
I have an Olympic lower that I don't know its origins. I bought this Franken build a while ago, and it ran ok so far. The searches I've done on slam fires tell of the same test for releasing the hammer, holding the trigger and resetting the hammer, then letting trigger go. I've done that test and when I let the trigger go, the nose catches the hammer as it should. I just cleaned the bolt/firing pin completely clean with Gun Scrubber aersol and reoiled, and it still slam fired on the 4 round today; then over and over every few rounds. What else besides the trigger, bolt face fouling, or high primers can cause this?
11/6/2012 8:46:32 PM EDT
[#1]
Check to see if your hammer pin is broken.
11/6/2012 11:25:43 PM EDT
[#2]
Thanks; just took it apart. Hammer pin is fine, the hammer itself looks right on as well. Hardly any wear at all in there; looks new. Wish I could figure this out. I've had it happen with other AR's before, but cleaning the bolt and firing pin fixed it. I don't get this.
11/7/2012 12:21:39 AM EDT
[#3]
Is the hammer  a notched hammer or rounded top?
11/7/2012 2:29:02 AM EDT
[#4]
Check the disconnector spring, could be broken or not seated correctly.
11/7/2012 4:18:20 AM EDT
[#5]
A weak disco spring will cause that problem.
I ran into a batch of them a long time ago.
11/7/2012 12:00:11 PM EDT
[#6]
I didn't know much about the triggers on these, so watched a few videos etc, and took mine apart. Photos below. All the edges look solid, and springs are strong. Disconnector looks good, as does it's spring (not sure how long it should be though). I did the test for holding trigger, reset hammer, and let it go: the nose caught the hammer as it should. Does anyone see anything weird in the photos (I know the 2nd pin is not in photo):

https://lh4.googleusercontent.com/-Vdjk3BM43bk/UJrIZrLf-FI/AAAAAAAACCc/XewWxpEV288/s693/trigger+006.JPG

https://lh6.googleusercontent.com/-KW04eTk393w/UJrIY6cO1II/AAAAAAAACCc/oseIyAcN5vg/s693/trigger+005.JPG

https://lh4.googleusercontent.com/-Vdjk3BM43bk/UJrIZrLf-FI/AAAAAAAACCc/XewWxpEV288/s693/trigger+006.JPG
11/7/2012 1:28:00 PM EDT
[#7]
I'm comparing the disconnector with the one inside an unfired lower I have, and that one has sharp square edges. This one in suspect is in fact all worn along the front edge that catches the nose, and even more heavily along one side versus the other. It wasn't obvious at first, but the front edge of the disconnector is worn all uneven. It's still catching the nose when I do that hold the trigger/set the hammer test, so I figured it must be good to go. Maybe its worn just enough to function sometime, but not always under firing conditions?
11/7/2012 3:59:42 PM EDT
[#8]
Quoted:
I'm comparing the disconnector with the one inside an unfired lower I have, and that one has sharp square edges. This one in suspect is in fact all worn along the front edge that catches the nose, and even more heavily along one side versus the other. It wasn't obvious at first, but the front edge of the disconnector is worn all uneven. It's still catching the nose when I do that hold the trigger/set the hammer test, so I figured it must be good to go. Maybe its worn just enough to function sometime, but not always under firing conditions?


Replace the complete fire control pack. Trigger sshouldn't wear out like that unless someone worked on it and messed things up by smoothng to deep.
12/14/2012 12:39:20 PM EDT
[#9]
Just wanted to update that I got a $6 disconnector at the gun show here last week, and took the Oly to the range. Fired 200 flawless rounds. Thanks so much everyone for the input; really grateful I could get right to the solution quick and easy like this.
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